One of the jobs I least like doing in DIY is cutting interior and exterior angles on crown moldings. It really is one of those jobs that the more experience you have at it the easier it becomes, which is why many DIY enthusiasts have problems cutting angles for crown molding; we simply don’t do it very often and never get that ‘feel’ for it.

Tools for the Job

There is no doubt that having the right tools for any DIY job will always make doing the job easier. When you need to cut an angle in a crown molding having the correct saw for the size and type of molding is one important thing the other really essential thing is to have a top quality miter in order to get the cutting angles correct.

However, now you can buy what is known as a compound miter jig. This is a device that has a miter and a saw (which is often powered), set at the correct angle, meaning so long as you’ve measured the length of the crown molding correctly - you’ll get a perfect corner every time.

Measurements for Cutting Angles

The technique for measuring the length of molding required for an internal or external angle is slightly different. When doing this - applying the old carpenter’s maxim is to be advised; “Measure twice - Cut once”. The following presumes you’re dealing with right-angle, 90 degree, corners.

Internal angles - measuring for an internal angle is quite easy. Just measure from one corner to another or from the end of a piece of crown molding already installed to the corner. That is the length of crown molding you need to cut, ready to have the angle cut into it.

External angles - these are slightly more difficult to measure. Again measure the length of molding you need to reach the corner, and then add to that measurement the width of the crown molding.

If you’ve got a short length of wall to fit a piece of crown molding into you might have one end needing an interior angle and the other needing an exterior angle. It’s a good tip to mark the respective ends, on the underneath side, with an "I" and an "E" to avoid any mistake when actually cutting the angles.

Cutting a Molding Angle

Regardless of what tools you’re using for this job I’d always practice on a few bits of ‘off-cut’ before working on a length of crown molding that is going to actually be used. If you have a compound miter jig then cutting the angles is fairly straightforward. All you need to do is make sure you position the length of crown molding correctly and let the jig take care of everything else.

If you’re using a miter template and saw, first please do read the instruction for the miter carefully. Positioning and using a crown molding miter is not the same as an ordinary miter block. Getting the angle of cutting through, as well as across, the molding is absolutely essential.

Position the template miter so that it fits snugly on to the molding. In order to obtain an angled cross-section through the molding; rest the blade of the saw you’re going to use on the sloping face of the miter and then cut through the molding. Do the same for the companion length of molding and you should have a good ‘flush’ fitting joint. When resting the saw blade on the miter be careful not to press down on to the miter as it may well spread out from its true angle.